Friday, November 17, 2017

Mapping Earthquake Prone Buildings

The New Zealand Herald has created an interesting mapped tour of Wellington's Earthquake Prone Buildings. The map shows the location of the 95 Wellington buildings which have unreinforced masonry and the 699 buildings which are earthquake prone. The map also identifies hotspots where unsafe buildings are located in areas with large numbers of pedestrians.

The map effectively uses Mapbox GL to provide a bird's eye view of Wellington with 3d buildings (the earthquake prone buildings are colored red on the map). This 3d view of the city is combined with a story map format so that the Herald can take its readers on a tour of the city's vulnerable buildings and dangerous hotspots.

The map uses extrusions to display the 3d buildings. This is neatly combined with the story map format to give a real sense of flying over the city's buildings. This tour of the city is supported by the Herald's analysis of the city's earthquake prone buildings and the danger that they pose to the city. This analysis appears in the scrolling map side-panel.

In New Zealand all buildings need to be assessed by law to identify which buildings are earthquake prone. The New Zealand Herald were able to use this data to create their map of Wellington's earthquake prone buildings. In the United States the Oregonian had to take a different approach in mapping the Oregon buildings most prone to earthquake damage.

In 1974 Oregon enacted its first statewide building code. In 1993 western Oregon adopted its first seismic standards. Franz Rad, a professor of civil & environmental engineering at Portland State University, argues that these dates provide a "broad-brush look at the vulnerability of buildings".

Earthquakes: How Vulnerable are Portland’s Buildings? uses Portland building age data to assess which buildings are most earthquake prone. Building footprints are colored on the map to show buildings constructed before 1974, those constructed between 1974 & 1993 and buildings erected after 1993. You can therefore use the map to assess the ('broad-brush') vulnerability of any Portland building to earthquake damage.